1. Field of the Invention
The present invention relates to an electrolytic material formulation, an electrolytic material polymer formed from the electrolytic material formulation. In particular, the present invention relates to a solid capacitor using the electrolytic material polymer.
2. Descriptions of the Related Art
A capacitor is an electronic component widely used in various electronic products. Due to the development of miniaturized and lightweight electronic products, a capacitor with a smaller size, a higher electric capacity and a high-voltage applicable is required.
Generally, the capacitor can be categorized into liquid state capacitors and solid capacitors. Liquid state capacitor(s), such as aluminum liquid capacitor(s), use liquid electrolyte(s) as charge conducting media, wherein the liquid electrolyte(s) generally include high boiling alcohol(s), ionic liquid(s), boric acid, phosphoric acid, organic carboxylic acid(s), ammonium salt(s), high-polar organic solvent(s), a small amount of water, etc. The above ingredients can function as charge conducting media and repair the damaged dielectric layer on the anode surface of the capacitor as well. In the case of a aluminum liquid state capacitor where aluminum and aluminum oxide are respectively used as anode and a dielectric layer thereon, the aluminum layer will be exposed if defects occur on the dielectric layer and result in current leakage.). The liquid electrolytes will react with exposed aluminum metal to form aluminum oxide during the charging/discharging process, and the dielectric layer is thus, repaired. However, liquid state capacitor(s) usually have disadvantages, such as low conductivity, and weak heat resistance. In addition, during the repair of the dielectric layer, hydrogen is generated and this may cause the capacitor to explode and thus, damage the electronic products.
Solid state capacitor(s) use solid state electrolyte(s) as charge conducting media, with examples including organic semiconductor complex salts (e.g., tetracyanoquinodimethane (TCNQ)), inorganic semiconductors (e.g., MnO2) and conducting polymer(s), wherein the preference is given to conducting polymer(s) with superior heat resistance and high conductivity. The solid capacitor has advantages, such as a long lifetime, superior stability, low equivalent series resistance (ESR), low capacitance change rate, and superior heat resistance and current endurance. As compared with liquid capacitor(s), solid state capacitor(s) do not have the risk of electrolyte leakage or capacitor explosion. In view of the above, the industries have all focused on the research and development of solid state capacitor(s).
U.S. Pat. No. 4,609,971 discloses a solid state capacitor using a conductive polymer. The solid state capacitor contains a conductive polyaniline polymer and is obtained by immersing the anode aluminum foil of the capacitor into a solution containing conductive polyaniline powders and LiClO4 dopant, and then removing the solvent from the aluminum foil. However, the molecule size of polyaniline is too big to permeate into the micropores of the anode aluminum foil, and thus, the immersing performance is bad and the resistance of the obtained capacitor is high. To help the polymer penetrate into the micropores of the anode aluminum foil more easily, U.S. Pat. No. 4,803,596 discloses a method for preparing solid state capacitor(s) using conductive polymer(s) as electrolyte(s) by chemical oxidative polymerization. The method is carried out by immersing the anode aluminum foil into a conductive polymer monomer-containing solution and an oxidizing agent-containing solution respectively, and polymerizing the conductive polymer monomer, wherein the immersion and polymerization processes are repeated several times to form sufficient conductive polymer electrolytes. U.S. Pat. No. 4,910,645 discloses an aluminum solid state capacitor using poly-3,4-ethylenedioxythiophene (PEDOT) as an electrolyte, wherein the electrolyte is prepared using 3,4-ethylenedioxythiophene (EDOT) along with iron (III) p-toluenesulfonate (oxidizing agent). PEDOT is widely used as an electrolyte of solid state capacitor(s) in view of the advantages of superior heat resistance, high conductivity, high charge conducting rate, avirulence, a long lifetime, etc. However, the particle size of the conductive polymer thus formed is not uniform and has a wide distribution, i.e., has a large span value. The firstly formed conductive polymer molecules will aggregate with each other to weaken the mobility of unreacted monomer and oxidizing agent molecules and thus, lead to an incomplete polymerization. As a result, it is difficult to provide a completely and highly polymerized polymer structure on the surface and pores of the electrode (e.g., an aluminum foil). The polymer mainly presents in a form of a powder, which is difficult to adhere onto the surface and instead falls through the pores of the electrode. As a result, a solid state capacitor using PEDOT has a weak stability at high voltage (e.g., higher than 16 V) and limited working voltage. Therefore, the industries are all expected to develop a solid capacitor with superior withstand voltage and stability.